Iterative 3D Depth Model Building via One-Pass 3D Depth Migration

Abstract

With the advent of steep-dip non-dispersive Isotropie 3D time and depth migration algorithms, the ability to image complex structures has entered a riew phase. However, the most important issue in subsurface imaging is nor the migration algorithm, but the elaboration of the subsurface velocity model. Many conventional approaches to obtaining a migration velocity field involve Dix inversion of RMS stacking veloeities. with appropriate editing and smoothing, leading to image ray, or normal ray map migration of picked time horizons to produce a final depth model.

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“…With each technique, there are various theoretical or practical limitations. For example, the poststack layer-stripping approach (Jones, 1993) presupposes that the velocities are known, and then updates the layer geometries. The Deregowski-loop (Deregowski, 1990) allocates a vertical 1D velocity estimate to an incorrect spatial location; the coherency scan ('inversion') technique supposes constant velocities within the 3D ray-bundle (Reshef, 1994); 3D Tomographic inversion (Diet, et al, 1994) supposes a smooth model.…”